Macrophages in normal cycling human ovaries; immunohistochemical localization and characterization

We evaluated the immunolocalization and characterization of macrophages in 28 normal cycling human ovaries. Two primary antibodies were used to detect the macrophages: PGM1, a general marker for macrophages, and 25F9 which is specific for phagocytosing macrophages. Spindle-shaped cells positive for PGM1 but negative for 25F9 were observed in the stroma (123.6 ± 1.05 cells/10^-6 m²) and theca layer of the follicle (mean ranged from 22.61 to 53.79) and the number of these cells did not change throughout the cycle. After ovulation, PGM1 positive cells with ballooning bodies began to appear in the early corpus luteum (111.8 ± 0.83). The number of these macrophages increased in the mid and late corpora lutea, and reached maximum in the early degenerating corpus luteum (1231.0 ± 3.29). A lower number of PGM1 positive ballooning macrophages were observed in the atretic follicle (177.9 ± 1.42), 25F9 positive cells were also observed among the PGM1 positive balloon-shaped cells. The number of cells double positive for 25F9 and PGM1 was observed in the mid corpus luteum (44.6 ± 0.46), increased in the late corpus luteum and early degenerating corpus luteum, and reached plateau in the late degenerating corpus luteum (549.0 ± 5.82). A lower number of these double positive macrophages were also observed in the atretic follicle (64.8 ± 0.36). The ratio of 25F9 to PGM1 positive cells increased in parallel with ageing of the corpus luteum (0.19 in the mid corpus luteum, 0.39 in the late corpus luteum, and 0.37 in the early degenerating corpus luteum), and the great majority of PGM1 positive cells were also immunopositive for 25F9 in the late degenerating corpus luteum (0.81). These results suggest that in normal cycling human ovaries, macrophages are mainly involved in luteal regression as scavengers.